Understanding how an audio compressor works can be hard when you’re new to mixing. And most of the guides stretch what they are going to explain which makes it boring to read or listen. There are only 7 easy terms to know. After that, you can use any compressor successfully.
Lets get started.
What is a Compressor
Compression is for reducing the dynamic range of an audio signal. A compressor is an automatic volume knob which turns down the volume level when it gets loud. At its basic description, an audio compressor is just an automatic volume fader control.
The seven definitions we are going to analyze are:
1. Gain Reduction Meter
This shows how much gain is being reduced by the compressor. The more gain is decreased, the more the compressor is working.
The volume level where the compressor will start working. If the audio volume is louder than the threshold level, the compressor will be activated. If you lower the threshold, more audio will be compressed.
So basically we set the Threshold to where we want to keep the keep the audio signal level.
Determines by how much the volume is reduced. The higher the ratio, the more aggressive the compression. To read a ratio, flip the numbers around. For example, a ratio of 4:1 means that for every 1dB that goes above the threshold, 1/4th of a dB comes out.
Keep the ratio around 1.5:1 and 3:1 for natural presence unless you have to hardly compress (for example highly compressed hip hop vocals)
4. Attack Time
Determines how quickly the compressor completely engages and reduces the volume of the audio. Faster attack times make an instrument thick and controlled.
Slower attack times make an instrument punchy and exciting. Unless you have a reason, this is usually preferred. So basically attack time is how fast the compressor will start to work and reduce the volume.
5. Release Time
Determines how long it takes the compressor to completely disengage and return the audio to its normal level.
This means after the compressor starts working, how long does it take to stop.
Determines how aggressive the compression sounds. A “soft knee” (1.0) makes the compression more subtle.
A “hard knee” (0.0) makes the compression more obvious.
7. Makeup Gain
Increases the output level to compensate for the loss in volume due to compression.
Use makeup gain to keep your instrument from getting quieter in the mix.
So as you can see, practically there are seven easy definitions to know when using an audio compressor. So first you set the threshold, and then you arrange the ratio, attack and release time. After that you keep an eye on the gain reduction meter. If you think your audio signal is quiet than you want, you add some make up gain.